Position detecting system and position detecting program

ABSTRACT

A plurality of positional information transmitters  100 , each of which transmits positional information to which a plurality of unit spaces are each uniquely assigned, are disposed on a ceiling. A mobile terminal  10  receives the positional information transmitted from each of the positional information transmitters  100  and changes a terminal-side image in accordance with the received positional information. Furthermore, the mobile terminal  10  transmits to a server  300  current positional information and operation information indicating an instruction inputted by a user. The server  300  changes, in accordance with the current positional information and the operation information received by the mobile terminal  10 , a floor image displayed on a plurality of floor displays  200  disposed on a floor. Thus, it becomes possible to provide a highly interesting and novel position detecting system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 11/450,451, filedJun. 12, 2006, which claims the benefit of Japanese Patent ApplicationNo. 2005-297969, each of which is incorporated herein in its entirety.

BACKGROUND

1. Field of the Technology

The technology presented herein relates to a position detecting systemand a position detecting program.

2. Description of the Background Art

Japanese Laid-Open Patent Publication No. 1-292916 (hereinafter,referred to as patent document 1) discloses a system in which positionalinformation transmitted from an infrared transmitter is received bymeans of a transponder, and then transmitted to an information center,thereby determining a position of a person carrying the transponder.

Japanese Laid-Open Patent Publication No. 2000-98034 (hereinafter,referred to as patent document 2) discloses a system in which positionalinformation transmitted from an infrared transmitter is received bymeans of a mobile terminal, and an image displayed on a screen of themobile terminal is changed based on the received positional information.Specifically, as shown in FIG. 6 of patent document 2, a drawing of aroom is previously displayed on the screen of the mobile terminal, andbased on the received positional information, a route from a currentposition to a destination is superimposed on the drawing of the room tobe displayed.

However, in the system disclosed in patent document 1, an imagedisplayed on a screen of the transponder is not changed based on thereceived positional information. In addition, in the system disclosedtherein, the image displayed on a display device other than thetransponder (e.g., a display device controlled by the informationcenter) is not changed based on the positional information received bymeans of the transponder and operation information indicating anoperation inputted on the transponder by a user.

Furthermore, in the system disclosed in patent document 2, although theimage displayed on the screen of the mobile terminal is changed based onthe received positional information, an image displayed on a displaydevice other than the mobile terminal is not changed based on thepositional information received by means of the mobile terminal andoperation information obtained by operating the mobile terminal.

SUMMARY

Therefore, a feature of an example embodiment presented herein is toprovide a position detecting system and a position detecting programcapable of changing an image displayed on a mobile terminal based onpositional information received by the mobile terminal, and capable ofchanging an image displayed on an external display device based on thepositional information received by the mobile terminal and operationinformation obtained by operating the mobile terminal.

The position detecting system of the present embodiment comprises: apositional information transmission device (100, 400) for transmittingpositional information; a mobile terminal (10) for receiving thepositional information; and a control device (200, 300) capable ofcommunicating with the mobile terminal.

The positional information transmission device includes a plurality ofpositional information transmitters (100) for transmitting thepositional information to which a plurality of unit spaces are eachuniquely assigned.

The mobile terminal includes: first display means (11, 12) fordisplaying a first image; first receiving means (34) for receiving thepositional information transmitted from the positional informationtransmitters; first image processing means (21) for changing the firstimage in accordance with the positional information received by thefirst receiving means; operation means (14, 15) for accepting aninstruction inputted by a user; and transmission means (33) fortransmitting to the control device current positional informationcorresponding to the positional information received by the receivingmeans and operation information indicating the instruction inputted bythe user through the operation means.

The control device includes: second display means (200) for displaying asecond image; second receiving means (303) for receiving the currentpositional information and the operation information transmitted fromthe mobile terminal; and second image processing means (302) forchanging the second image in accordance with the current positionalinformation and the operation information received by the secondreceiving means.

According to a first preferred variant of the position detecting systemof the present embodiment, the second image processing means selects apartial area of the second image, the partial area corresponding to acurrent position of the mobile terminal, based on the current positionalinformation received by the second receiving means, and changes theselected partial area of the second image in accordance with theoperation information received by the second receiving means.

According to a second preferred variant of the position detecting systemof the present embodiment, the plurality of positional informationtransmitters are disposed on a ceiling, and the second display means isdisposed on a floor.

According to a third preferred variant of the position detecting systemof the present embodiment, each of the positional informationtransmitters transmits the positional information for a predeterminednumber of times at an interval of a predetermined period of time, andthe mobile terminal further includes current positional informationgenerating means for measuring, for the predetermined period of time, areceiving time of each piece of the positional information received bythe first receiving means, and generating the current positionalinformation based on the receiving time of the each piece of thepositional information.

According to a fourth preferred variant of the position detecting systemof the present embodiment, the current positional information generatingmeans generates the current positional information indicating a positionwhich is more accurate than that indicated by the positionalinformation, based on a ratio of the receiving time of each piece of thepositional information received, for a period of time, by the firstreceiving means, to a transmission time of the each piece of thepositional information transmitted for the period of time.

According to a fifth preferred variant of the position detecting systemof the present embodiment, the current positional information generatingmeans calculates a weighted average of two-dimensional coordinatesindicating the positional information by dividing a sum of thepositional information received for the period of time by the firstreceiving means, in accordance with a total receiving time of thepositional information, such that the current positional informationmeans generates the current positional information.

According to a sixth preferred variant of the position detecting systemof the present embodiment, the first image processing means changes thefirst image in accordance with the positional information received bythe first receiving means such that the first image includes adescription text corresponding to the received positional information.

According to a seventh preferred variant of the position detectingsystem of the present embodiment, the first image includes one of anselectable button image and a non-selectable button image, which arechanged in accordance with the positional information received by thefirst receiving means, and the first image processing means changes adisplay mode of the button image in accordance with the positionalinformation received by the first receiving means.

According to an eighth preferred variant of the position detectingsystem of the present embodiment, the operation information includesinstruction information indicating an enlargement display instruction,and the second image processing means enlarges, in accordance with theinstruction information indicating the enlargement display instruction,a portion of the second image centering on a position of the secondimage, the position corresponding to the current positional informationreceived by the second receiving means.

According to a ninth preferred variant of the position detecting systemof the present embodiment, the operation information includesinstruction information indicating a guide request instruction, and thesecond image processing means adds, in accordance with the instructioninformation indicating the guide request instruction, a mark for guidingthe user to a predetermined position, on a position of the second image,the position corresponding to the current positional informationreceived by the second receiving means.

A computer-readable storage medium stores a position detecting programexecuted by a computer (21) of a mobile terminal and a computer (302) ofa control device in a position detecting system comprising: a positionalinformation transmission device (100, 400) including a plurality ofpositional information transmitters (100) for transmitting positionalinformation to which a plurality of unit spaces are each uniquelyassigned; the mobile terminal (10) for receiving the positionalinformation; and the control device capable of communicating with themobile terminal.

The position detecting program instructs the computer (21) of the mobileterminal to perform: first display control means for causing firstdisplay means (11, 12) of the mobile terminal to display a first image;first receiving control means for causing first receiving means (34) ofthe mobile terminal to receive the positional information transmittedfrom the positional information transmitters; first image processingmeans for changing the first image in accordance with the positionalinformation received by the first receiving means; and transmissioncontrol means for causing transmission means (33) of the mobile terminalto transmit to the control device current positional informationcorresponding to the positional information received by the receivingmeans and operation information, inputted by operation means of themobile terminal, which indicates an instruction of a user.

Furthermore, the position detecting program instructs the computer (302)of the control device to perform: second display control means forcausing second display means (200) of the control device to display asecond image; second receiving control means for causing secondreceiving means (303) of the control device to receive the currentpositional information and the operation information transmitted fromthe mobile terminal; and second image processing means for changing thesecond image in accordance with the current positional information andthe operation information received by the second receiving means.

According to the position detecting system of the present embodiment,the mobile terminal receives the positional information, whereby thefirst image displayed on the first display means of the mobile terminalis changed. Furthermore, the current positional information generatedbased on the positional information received by the mobile terminal andthe operation information indicating the instruction inputted by theuser through the operation means are transmitted from the mobileterminal to the control device, whereby the second image displayed onthe second display means of the control device is changed. Thus, itbecomes possible to provide a highly interesting and novel positiondetecting system.

According to the first preferred variant of the position detectingsystem of the present embodiment, a portion of the second imagedisplayed on the second display means, the portion corresponding to thereceived current positional information is changed. Thus, a portion ofthe second image, the portion corresponding to the current positionalinformation of the mobile terminal can be changed in accordance with theoperation information.

According to the second variant of the position detecting system of thepresent embodiment, the second display means is disposed on the ground,thereby making it possible to provide a visual effect which changes animage displayed on the user's feet when the user operates the mobileterminal.

According to the third variant of the position detecting system of thepresent embodiment, even when the mobile terminal can receive aplurality of pieces of the positional information, the currentpositional information is generated based on a receiving frequency ofeach of the pieces of the positional information, thereby making itpossible to accurately detect the current position of the mobileterminal.

According to the fourth variant of the position detecting system of thepresent embodiment, the current positional information is detected basedon the ratio of the receiving time of each piece of the positionalinformation to the transmission time of each piece of the positionalinformation, thereby making it possible to detect the current positionof the mobile terminal, the current position being more accuratelyindicated than that indicated by the positional information.

According to the fifth variant of the position detecting system of thepresent embodiment, the current position of the mobile terminal can beeasily obtained by calculating the weighted average of the receivedpositional information.

According to the sixth variant of the position detecting system of thepresent embodiment, when the user carrying the mobile terminal moves toa location, the description text corresponding to the location can beautomatically displayed on the first display means of the mobileterminal.

According to the seventh variant of the position detecting system of thepresent embodiment, the button image displayed on the first displaymeans of the mobile terminal can be selectable only when the usercarrying the mobile terminal is in a specific position. Furthermore, thedisplay mode of the button image is changed, thereby making it possibleto inform the user whether the button image is selectable ornon-selectable.

According to the eighth variant of the position detecting system of thepresent embodiment, the user can enlarge a portion of the second imagedisplayed on the second display means, the portion corresponding to thecurrent position of the mobile terminal carried by the user.

According to the ninth variant of the position detecting system of thepresent embodiment, the user can be guided to a destination based on thesecond image displayed on the second display means.

These and other features, aspects and advantages of the presentembodiment will become more apparent from the following detaileddescription of the present embodiment when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a position detecting system;

FIG. 2 is a view illustrating a positional relationship betweenpositional information transmitters 100 and a floor display 200;

FIG. 3 is a block diagram illustrating a configuration of the positiondetecting system;

FIG. 4 is an external view of a mobile terminal 10;

FIG. 5 is a block diagram illustrating an internal configuration of themobile terminal 10;

FIG. 6 is a block diagram illustrating an internal configuration of aserver 300;

FIG. 7 is an external view of the positional information transmitter100;

FIG. 8 is a view illustrating four emission ranges of infrared raysemitted from the positional information transmitter 100;

FIG. 9 is a view illustrating a unit space and a unit area;

FIG. 10 is a view illustrating the unit space as viewed horizontallytherefrom;

FIG. 11 is a view used for explaining a timing at which an infrared LEDis emitted;

FIG. 12 is a view used for explaining another timing at which aninfrared LED is emitted;

FIG. 13 is a view used for explaining still another timing at which aninfrared LED is emitted;

FIG. 14 is a view used for explaining still another timing at which aninfrared LED is emitted;

FIG. 15 is a view illustrating a relationship between a receivingposition of the positional information and a receiving frequency of thepositional information;

FIG. 16 shows an exemplary terminal-side image;

FIG. 17 shows another exemplary terminal-side image;

FIG. 18 shows an exemplary floor image including an arrow 46;

FIG. 19 shows another exemplary floor image;

FIG. 20 shows still another exemplary terminal-side image;

FIG. 21 shows still another exemplary floor image including an eventpicture 47;

FIG. 22 shows an exemplary transition of floor images enlarged by animage enlargement process;

FIG. 23 shows a memory map of a RAM 24 included in the mobile terminal10;

FIG. 24 shows an exemplary event table 51;

FIG. 25 shows exemplary receiving time data 53;

FIG. 26 shows a memory map of a RAM 301 included in the server 300;

FIG. 27 shows an exemplary “discover” event table 57;

FIG. 28 shows exemplary sightseeing course data 60;

FIG. 29 is a flowchart illustrating a flow of a process executed by aCPU core 20 of the mobile terminal 10; and

FIG. 30 is a flowchart illustrating a flow of a process executed by aCPU 302 of the server 300.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a position detecting system according to an embodiment willbe described in detail.

FIG. 1 shows an outline of the position detecting system according to anexample embodiment. In the present embodiment, a plurality of positionalinformation transmitters 100 are mounted on a ceiling, and a plurality(e.g., 70) of floor displays 200 are mounted on a floor. As shown inFIG. 2, above each of the floor displays 200, the plurality ofpositional information transmitters 100 are disposed in a form of amatrix. A user carrying a mobile terminal 10 can freely move on thefloor displays 200.

FIG. 3 is a block diagram illustrating an overall configuration of theposition detecting system according to the present embodiment. Each ofthe plurality of pieces of positional information transmitters 100mounted on the ceiling transmits an infrared ray at a predeterminedtiming in accordance with a control signal outputted from a transmittercontrol device 400. The infrared ray includes positional information.The positional information is used for determining a current position ofthe mobile terminal 10. Each of the plurality of floor displays 200mounted on the floor displays an image in accordance with a picturesignal outputted from a server 300. The mobile terminal 10 carried bythe user has a function of receiving infrared rays transmitted from thepositional information transmitters 100. Upon receiving the infraredrays transmitted from the positional information transmitters 100, themobile terminal 10 determines the current position thereof based on thepositional information superimposed on the infrared rays. Thereafter,the mobile terminal 10 transmits to the server 300, by radiocommunication, current positional information indicating the currentposition of the mobile terminal 10 and operation informationcorresponding to an operation inputted by the user. In accordance withthe current positional information and the operation information bothreceived from the mobile terminal 10, the server 300 changes the imagedisplayed on the floor displays 200 so as to correspond to the currentpositional information.

Next, the mobile terminal 10 will be described in detail. Although ahand-held game device is used as the mobile terminal 10 in the presentembodiment, it is understood that the present invention is not limitedthereto.

FIG. 4 is an external view of the mobile terminal 10. In FIG. 4, themobile terminal 10 includes a first LCD (Liquid Crystal Display) 11 anda second LCD 12. A housing 13 includes an upper housing 13 a and a lowerhousing 13 b, and the first LCD 11 is accommodated in the upper housing13 a, and the second LCD 12 is accommodated in the lower housing 13 b.Resolutions of the first LCD 11 and the second LCD 12 are both 256dots×192 dots. Note that although a LCD is used as a display device inthe present embodiment, any other display such as a display device usingan EL (Electro Luminescence) may be used. Also, the resolution of thedisplay device may be at any level.

The upper housing 13 a is provided with sound holes 18 a and 18 b foroutputting a sound from a pair of loudspeakers (30 a and 30 b shown inFIG. 5) to an exterior.

The lower housing 13 b is provided with input devices as follows; across switch 14 a, a start switch 14 b, a select switch 14 c, an “A”button 14 d, a “B” button 14 e, a “X” button 14 f, a “Y” button 14 g, a“L” button 14L, and a “R” button 14R. In addition, a touch panel 15 isprovided on a screen of the second LCD 12 as another input device. Thelower housing 13 b further includes a power switch 19, and insertionopenings for storing a memory card 17 and a stick 16. Note that if onlythe touch panel 15 is used as an input device, the cross switch 14 a,the start switch 14 b, the select switch 14 c, the “A” button 14 d, the“B” button 14 e, the “X” button 14 f, the “Y” button 14 g, the “L”button 14L, and the “R” button 14R may not be provided.

The touch panel 15 may be of any type such as a resistive film type, anoptical type (infrared type), or a capacitive coupling type. The touchpanel 15 has a function of outputting, when its surface is touched withthe stick 16, coordinate data which corresponds to a touch position. Thefollowing description is provided on an assumption that a player usesthe stick 16 to operate the touch panel 15. However, the touch panel 15may also be operated by a pen (stylus pen) or a finger instead of thestick 16. In the present embodiment, a touch panel 15 having aresolution at 256 dots×192 dots (detection accuracy) as same as thesecond LCD 12 is used. However, resolutions of the touch panel 15 andthe second LCD 12 may not necessarily be consistent with each other.

Furthermore, the mobile terminal 10 includes two infrared receivingunits 34, each of which is provided with the upper housing 13 a or thelower housing 13 b, for receiving the infrared rays transmitted from thepositional information transmitters 100. Each of the infrared receivingunits 34 must be disposed at a position so as not to be covered with ahand or a finger of the user carrying the mobile terminal 10. In thepresent embodiment, the two infrared receiving units 34 are disposed atcorners, on the mobile terminal 10, which are diagonally opposite toeach other with a distance therebetween. Thus, even if one infraredreceiving unit 34 were covered with the hand or the finger of the user,the other infrared receiving unit 34 could receive the infrared raystransmitted from the positional information transmitters 100.

The memory card 17 is a storage medium having a computer program (aposition detecting program) stored therein, and placed in the insertionslot provided at the lower housing 13 b in a removable manner.

Next, with reference to FIG. 5, an internal configuration of the mobileterminal 10 will be described in detail.

In FIG. 5, a CPU core 21 is mounted on an electronic circuit board 20which is to be housed in the housing 13. Via a bus 22, the CPU core 21is connected to a connector 23, an input/output interface circuit (shownas I/F circuit in the diagram) 25, a first GPU (Graphics ProcessingUnit) 26, a second GPU 27, a RAM 24, a LCD controller 31, a wirelesscommunication unit 33 and the infrared receiving units 34. The memorycard 17 is connected to the connector 23 in a removable manner. Thememory card 17 includes a ROM 17 a for storing the position detectingprogram and a RAM 17 b for storing backup data in a rewritable manner.The position detecting program stored in the ROM 17 a of the memory card17 is loaded to the RAM 24, and the position detecting program havingbeen loaded to the RAM 24 is executed by the CPU core 21. The RAM 24stores, in addition to the position detecting program, data such astemporary data which is obtained by the CPU core 21 executing theposition detecting program, and image data. To the I/F circuit 25 areconnected, the touch panel 15, the right loudspeaker 30 a, the leftloudspeaker 30 b and an operation switch unit 14, comprised of the crossswitch 14 a, the “A” button 14 d, and others, as shown in FIG. 4. Theright loudspeaker 30 a and the left loudspeaker 30 b are arranged in aninterior of the sound holes 18 a and 18 b, respectively.

A first VRAM (Video RAM) 28 is connected to the first GPU 26, and asecond VRAM 29 is connected to the second GPU 27. In accordance with aninstruction from the CPU core 21, the first GPU generates a first imagebased on the image data which is stored in the RAM 24, and writes imagesinto the first VRAM 28. The second GPU 27 also follows an instructionfrom the CPU core 21 to generate a second image, and writes images intothe second VRAM 29. The first VRAM 28 and the second VRAM 29 areconnected to the LCD controller 31.

The LCD controller 31 includes a register 32. The register 32 stores avalue of either 0 or 1 in accordance with an instruction from the CPUcore 21. When the value of the register 32 is 0, the LCD controller 31outputs to the first LCD 11 the first image which has been written intothe VRAM 28, and outputs to the second LCD 12 the second image which hasbeen written into the second VRAM 29. When the value of the resister 32is 1, the first image which has been written into the first VRAM 28 isoutputted to the LCD 12, and the second image which has been writteninto the second VRAM 29 is outputted to the first LCD 11.

The wireless communication unit 33 provides a function of performingwireless communication with a server 300 and other mobile terminals, sothat various types of information are exchanged therebetween.

Further, the configuration of the mobile terminal 10 as described aboveis merely an example. The mobile terminal of the present invention mayinclude at least a function of displaying an image, a function ofreceiving a signal outputted from the positional informationtransmitters, a function of detecting an operation inputted by the user,and a function of transmitting a signal to the server 300.

Next, the server 300 will be described in detail.

The server 300 includes a RAM 301, a CPU 302, a wireless communicationunit 303, a hard disk 304, and a picture signal outputting unit 305. Thehard disk 304 stores a computer program (i.e., the position detectingprogram) and image data. The position detecting program is loaded to theRAM 301, and the position detecting program having been loaded to theRAM 301 is executed by the CPU 302. The RAM 301 stores, in addition tothe position detecting program, data such as temporary data which isobtained by the CPU 302 executing the position detecting program, andimage data. The wireless communication unit 303 provides a function ofperforming wireless communication with the wireless communication unit33 of the mobile terminal 10. The picture signal outputting unit 305outputs a picture signal based on the image data generated by the CPU302 to each of the floor displays 200.

Although the present embodiment illustrates an example where theposition detecting program according to the present invention isprovided to the mobile terminal 10 and the server 300 via an externalstorage medium such as the memory card 17, the present invention is notlimited thereto. The position detecting program may be provided to themobile terminal 10 and the server 300 via a wire communication line or awireless communication line. Alternatively, the position detectingprogram may previously be stored in nonvolatile memories provided in themobile terminal 10 and the server 300.

In the following description, when necessary, the position detectingprogram executed at a side of the mobile terminal 10 is referred to as a“terminal-side position detecting program”, and the position detectingprogram executed at a side of the server 300 is referred to as a“server-side position detecting program”.

Next, a structure of the positional information transmitter 100 will bedescribed. As shown in FIG. 7, the positional information transmitter100 is structured such that a housing thereof contains four infraredLEDs (Light Emitting Diodes). All infrared rays emitted from theinfrared LEDs (a first LED, a second LED, a third LED, and a fourth LED)are emitted from the ceiling to the floor. However, these infrared raysare not emitted in parallel with each other (i.e., the infrared rays arenot emitted vertically with respect to the floor). Each of the infraredrays is emitted, as shown in FIG. 8, diagonally outward from the ceilingto the floor. Note that an emission range of each of the infrared LEDscan be adjusted to a certain extent by changing a length of acylindrical member, shown in FIG. 7, through which an infrared raypasses.

Then, a method of transmitting the positional information by means ofthe positional information transmitters 100 will be described. As shownin FIG. 9, the positional information transmitters 100 are disposed onthe ceiling in the form of a matrix. Hereinafter, as shown in FIG. 9, aspace defined by a rectangular parallelepiped having four positionalinformation transmitters 100 a to 100 d as vertexes is referred to as a“unit space”, and a floor face, which is one of six faces forming therectangular parallelepiped, is referred to as a “unit area”. Each of thepositional information transmitters 100 a to 100 d shown in FIG. 9 hasthe structure shown in FIG. 7. Among the four infrared LEDs included ineach of the positional information transmitters 100 a to 100 d, oneinfrared LED provided in an interior of the unit space is used to emitan infrared ray to the unit space having the positional informationtransmitters 100 a to 100 d as vertexes. Thus, four infrared rays arerespectively emitted from the positional transmitters 100 a to 100 d tothe unit space, and the same positional information (i.e., positionalinformation to which a plurality of unit spaces are each uniquelyassigned) is superimposed on the four infrared rays. As a result, if themobile terminal 10 is positioned, for example, in the unit space shownin FIG. 9, the mobile terminal 10 receives an infrared ray emitted fromat least any one of the positional information transmitters 100 a to 100d, thereby specifying the unit space in which the mobile terminal 10itself is positioned.

Although the present embodiment illustrates an example where, as shownin FIG. 9, the four infrared rays sharing the same positionalinformation are emitted from different directions to the unit space, thepresent invention is not limited thereto. For example, only one infraredLED may be provided on a center portion of a ceiling face forming eachunit space. However, as described in the present embodiment above, it ismore preferable that the four infrared rays sharing the same positionalinformation be emitted from different directions to the unit space. Insuch a configuration, as shown in FIG. 10, even if an infrared rayemitted from one positional information transmitter 100 did not reachthe infrared receiving units 34 of the mobile terminal 10 because theinfrared ray is interrupted by a head of the user, another infrared ray,having the same positional information as the interrupted infrared raysuperimposed thereon, which is emitted from the other positionalinformation transmitter 100, would reach the infrared receiving units 34of the mobile terminal 10, thereby more accurately specifying thecurrent position of the mobile terminal 10.

Furthermore, although the present embodiment illustrates an examplewhere the positional information transmitters 100 are mounted on theceiling, the present embodiment is not limited thereto. The positionalinformation transmitters 100 may be mounted on the floor, or on both theceiling and the floor.

Next, a transmission timing at which the positional informationtransmitter 100 transmits the positional information will be described.

In the present embodiment, infrared rays amplitude modulated by means ofthe positional information are emitted from the infrared LEDs. Also, theinfrared rays emitted from the infrared LEDs have common frequencybands. Therefore, when a plurality of infrared rays, each of which hasdifferent positional information superimposed thereon, simultaneouslyreach the infrared receiving units 34 of the mobile terminal 10, anerror occurs due to interference. Thus, in the present embodiment, inorder to prevent such an error caused by the interference, thetransmitter control device 400 controls a timing at which each of theinfrared LEDs is emitted such that when an infrared ray is emitted to aunit space, infrared rays for adjacent unit spaces are not emitted.

Hereinafter, with reference to FIGS. 11 to 14, a control, executed bythe transmitter control device 400, of a timing at which each of theinfrared LEDs is emitted, will be described in detail. FIGS. 11 to 14illustrate environments as viewed from over the positional informationtransmitters 100. Four circles, shown by dot-dash lines, in an interiorof each of the positional information transmitters 100 represent theinfrared LEDs, and a black circle among the four circles represents theinfrared LED transmitting the positional information.

In the present embodiment, the transmitter control device 400 causes theinfrared LEDs represented by black circles shown in FIG. 11 to emitinfrared rays during a first period of 25 m, causes the infrared LEDsrepresented by black circles shown in FIG. 12 to emit infrared raysduring a second period of 25 ms, causes the infrared LEDs represented byblack circles shown in FIG. 13 to emit infrared rays during a thirdperiod of 25 ms, and causes the infrared LEDs represented by blackcircles shown in FIG. 14 to emit infrared rays during a fourth period of25 ms. Thereafter, the transmitter control device 400 repeats a controlin a similar manner to that described above. Specifically, when n and mare integers, positional information (1+2n, 1+2m) is transmitted to aunit area (1+2n, 1+2m) during the first period of 25 ms, positionalinformation (1+2n, 2+2m) is transmitted to a unit area (1+2n, 2+2m)during the second period of 25 ms, positional information (2+2n, 1+2m)is transmitted to a unit area (2+2n, 1+2m) during the third period of 25ms, and positional information (2+2n, 2+2m) is transmitted to a unitarea (2+2n, 2+2m) during the fourth period of 25 ms. As such, fourpieces of the positional information are transmitted at an interval of100 ms.

In FIG. 11, the infrared rays containing four pieces of positionalinformation (1, 1), (1, 3), (3, 1) and (3, 3) are emitted to unit areas(1, 1), (1, 3), (3, 1) and (3, 3), respectively. Here, the infrared raycontaining the positional information (1, 1) is emitted not only to theunit area (1, 1) but also to a portion of unit areas adjacent to theunit area (1, 1). However, in the present embodiment, the currentposition of the mobile terminal 10 is determined, as described below,based on a receiving frequency of each piece of the positionalinformation. Thus, it is possible to determine the current position ofthe mobile terminal 10 even if the infrared ray is emitted, in additionto a unit area, to portions of other unit areas adjacent to the unitarea. An emission range of the infrared ray containing the positionalinformation (1, 1) may be a range which covers an entirety of the unitarea (1, 1) and is not overlapped with an emission range of asimultaneously emitted infrared ray containing the positionalinformation other than the positional information (1, 1). The same isalso true of other emission ranges of infrared rays containing otherpieces of the positional information.

Next, with reference to FIG. 15, the receiving frequency of thepositional information will be described. FIG. 15 is a view showing howa receiving frequency (i.e., a ratio of the number of times an infraredray is successfully received to a total number of times the infrared rayis emitted) of the positional information (2, 2) changes in accordancewith a position, of the mobile terminal 10, at which the infrared ray isreceived, when an infrared ray having positional information (2, 2)superimposed thereon is emitted to a unit area (2, 2) for a plurality oftimes. Note that characteristics of the receiving frequency depend on atype of the infrared LED, a structure of the positional informationtransmitter 100, performance quality of the infrared receiving unit 34,a mounting position of the infrared receiving unit 34, or the like.Generally speaking, however, there is a tendency, as shown in FIG. 15,that the farther away from a center of the unit area (2, 2) a positionat which the infrared ray is received is, the lower the receivingfrequency of the positional information (2, 2) becomes.

As described above, there is a tendency that the farther away from acenter of a unit area a position at which an infrared ray is receivedis, the lower a receiving frequency of the positional informationcorresponding the unit area becomes. Thus, in the case where the mobileterminal 10 receives a plurality of pieces of the positionalinformation, the mobile terminal 10 compares receiving frequencies ofthe plurality of pieces of the positional information with each other,thereby specifying the current position of the mobile terminal 10. Forexample, during a certain period, it is assumed that various pieces ofpositional information are transmitted six times, and the mobileterminal 10 receives the positional information (2, 2) six times (i.e.,a receiving frequency of the positional information is 100%), andpositional information (2, 3) three times (i.e., a receiving frequencyof the positional information is 50%). In such a case, it is determinedthat the mobile terminal 10 is positioned on the unit area (2, 2)corresponding to the positional information which has been mostfrequently received (i.e., the positional information (2, 2)).

By detecting such a receiving frequency, a position which is moreaccurately indicated than that indicated by the positional informationcan be detected. In the above example, the mobile terminal 10 ispositioned on the unit area (2, 2), and taking into account that thereceiving frequency of the positional information (2, 3) is 50%, it isfurther determined that the mobile terminal 10 is at a positiondisplaced toward the unit area (2, 3) from the center of the unit area(2, 2). In particular, taking the characteristics of the receivingfrequency shown in FIG. 15 into consideration, it is also determinedthat an amount of the displacement is approximately a length equal to aquarter of that of a side of the unit area.

As one of easy methods for calculating an accurate current position ofthe mobile terminal 10, there is a method for calculating a weightedaverage of the positional information (represented by two-dimensionalcoordinates if not represented by other manners) by dividing a sum ofthe positional information received by the mobile terminal 10 inaccordance with its receiving time (or its receiving frequency). Forexample, during a certain period, it is assumed that the mobile terminal10 receives positional information (1, 1) twice, positional information(1, 2) six times, positional information (2, 1) once, and positionalinformation (2, 2) twice. In this case, the following expression: ((1,1)×2+(1, 2)×6+(2, 1)×1+(2, 2)×2)/(2+6+1+2) is calculated, therebyobtaining the calculated result (1.3, 1.7) as the current position ofthe mobile terminal 10. Note that the calculated result (1.3, 1.7)represents, when a length of a side of a unit area is 1, a positiondisplaced 0.3 toward a unit area (2, 1) and 0.7 toward a unit area (1,2) from a center of a unit area (1, 1).

As described above, the position which is more accurately indicated thanthat indicated by the positional information is detected for the currentposition of the mobile terminal 10, thereby reducing the number of thepositional information transmitters 100 required for achieving a desiredprecision for position detection. Thus, it becomes possible to decreasea cost of the position detecting system.

Next, with reference to FIGS. 16 to 22, an exemplary transition ofimages displayed on the first LCD 11 and the second LCD 12, and anexemplary transition of images displayed on the floor displays 200, forwhen the user carrying the mobile terminal 10 moves on the floordisplays 200, will be described.

FIG. 16 shows an initial image displayed on the first LCD 11 and thesecond LCD 12 of the mobile terminal 10. Hereinafter, in order tofacilitate the understanding of the following description, an imagedisplayed on the first LCD 11 and an image displayed on the second LCD12 are generically referred to as a “terminal-side image”. Theterminal-side image includes a description display field 40, an “Acourse” selecting button 41, a “B course” selecting button 42, an“enlarge” button 43, a “past” button 44, and a “discover” button 45. Theuser touches one of the buttons (more accurately, an area, on a screenof the second LCD 12, in which one of the buttons is displayed)displayed on the second LCD panel 12 via the touch panel 15 so as toinput an instruction in accordance with the button. Note that the“discover” button 45 is a unique button which is only selectable in aspecific situation. In the initial terminal-side image, the “discover”image 45 is non-selectable. Furthermore, in order to clearly recognizewhether the “discover” button 45 is selectable or non-selectable, adisplay mode of the “discover” button 45 changes between when the“discover” button 45 is selective and when the “discover” button 45 isnon-selective. For example, in a situation where the “discover” button45 is selectable, the “discover” button 45 is displayed, as shown inFIG. 20, in a normal manner. On the other hand, in a situation where the“discover” button 45 is non-selectable, the “discover” button 45 is, asshown in FIG. 16, grayed out. Although the present embodimentillustrates an example where the touch panel 15 is used to select abutton, the present invention is not limited thereto. Other inputdevices (e.g., the operation switch unit 14) may be used to select abutton.

On the other hand, a map image of a certain region (“Kyoto” in thepresent embodiment) is displayed on an entirety of the plurality offloor displays 200 as an initial image. The map image is generated bycombining a satellite image of the region, which is captured by asatellite, with images of a vehicle, a human and a bird, which are allgenerated by computer graphics. The images of the vehicle, the human andthe bird are animated so as to be displayed as if they were actuallymoving. By walking on the plurality of floor displays 200 displayingsuch a map image, the user can have a special feeling as if he or shewere actually walking over the region, thereby causing the user toexperience a novel sensation. Hereinafter, in order to facilitate theunderstanding of the following description, an image displayed on theplurality of floor images 200 is generically referred to as a “floorimage”.

FIG. 17 shows the terminal-side image immediately after the user toucheswith the stick 16 the “A course” selecting button 41 displayed on theinitial image shown in FIG. 16. When the user touches the “A course”selecting button 41, a description text indicating that the user isstarted to be guided along an “A course” is displayed on the descriptiondisplay field 40, and the “B course” selecting button 42 is grayed out.On the other hand, as shown in FIG. 18, an image combining the map imagewith an arrow 46 indicating a direction of a destination is displayed onthe floor display 200A on which the user stands. The user moves inaccordance with the arrow 46, thereby sequentially visiting a pluralityof destinations along a predetermined course (“A course” or “B course”).As described above, the user can virtually travel around a regiondisplayed on the floor displays 200. Hereinafter, such an operationmode, executed by the position detecting system, which guides the useralong the “A course” or the “B course” is referred to as a “sightseeingmode”.

When the user walks through a plurality of the floor displays 200 fromthe floor display 200A shown in FIG. 18 and arrives at a floor display200B, shown in FIG. 19, on which a destination at the present time(e.g., “Gojyo Ohashi Bridge”) is displayed, the terminal-side imagechanges from the image shown in FIG. 17 to an image shown in FIG. 20.The image shown in FIG. 17 is different from the image shown in FIG. 20in that a description text regarding “Gojyo Ohashi Bridge” is displayedon the description display field 40 in FIG. 20 and the “discover” button45 is changed from a grayed out state in FIG. 17 to a normal state inFIG. 20. As described above, when the user arrives in a vicinity of aposition at which a destination is displayed, a description textregarding the destination is automatically displayed on the descriptiondisplay field 40.

When the user touches the “discover” button 45 while the “discover”button 45 is displayed, as shown in FIG. 20, in a normal manner, anevent picture 47 corresponding to a location is displayed, as shown inFIG. 21, on one of the floor displays 200 (i.e., the floor display 200Bin the present embodiment) on which the user stands. In an example shownin FIG. 21, a picture of a monument constructed in the vicinity of“Gojyo Ohashi Bridge” is displayed as the event picture 47. Note thatsuch an event picture is also displayed in operation modes other thanthe sightseeing mode. Locations (e.g., 150) for displaying eventpictures are previously determined. When the user comes near one of thelocations, the “discover” button 45 changes from the grayed out state tothe normal state so as to notify him or her that there is an eventpicture corresponding to the location. Thus, the user can enjoy walkingaround while searching for a location at which an event picture is“hidden” as if he or she were searching for a treasure.

Irrespective of whether or not an operation mode executed by theposition detecting system is the sightseeing mode, when the user movesto a portion of the floor image, displayed on the floor displays 200,where he or she wishes to enlarge the displayed portion thereof, andthen touches the “enlarge” button 43 of the mobile terminal 10, thedisplayed portion of the floor image is to be enlarged. For example,when the user touches the “enlarge” button 43 while standing on thelower-left portion of the floor display 200B, an image displayed on thefloor display 200B is enlarged, as shown in FIG. 22, by two timescentering on a unit area on which the user is positioned. When the userfurther touches the “enlarge” button 43, the image of the floor display200B is further enlarged by two times centering on the unit area onwhich the user is positioned. As described above, the user can enlarge aportion of the floor image as he or she pleases. Note that in thepresent embodiment, the floor image is enlarged for each image displayedon one floor display 200. That is, in an example of enlarging the floorimage as shown in FIG. 22, the image displayed on the floor display 200Bon which the user is positioned is only enlarged, and images displayedon its adjacent floor displays 200 are not enlarged. However, thepresent invention is not limited to the above-described example. Anentire floor image may be enlarged centering on a unit area on which theuser is positioned (i.e., images displayed on all of the floor displays200 may be changed altogether).

When the user pushes the “past” button 44 displayed on the terminal-sideimage, the map image displayed on one of the floor displays 200 on whichthe user stands changes to a “past” image, i.e., an illustration showingwhat a region displayed on the floor displays 200 looked like onethousand and a few hundreds years ago (e.g., “Heiankyo” during the“Heian” Period). Thus, the user can view an illustration showing what adesired region looked like in the past.

Hereinafter, in order to realize the aforementioned transitions of theterminal-side images and the floor images, a process executed by theposition detecting system will be described in detail.

FIG. 23 shows a memory map of the RAM 24 included in the mobile terminal10. The RAM 24 stores a terminal-side position detecting program 50, anevent table 51, description data 52, and receiving time data 53. Theterminal-side position detecting program 50 stored in the ROM 17 a ofthe memory card 17 is loaded to the RAM 24, and the terminal-sideposition detecting program 50 having been loaded to the RAM 24 isexecuted by the CPU core 21. The event table 51 and the description data52 stored in the ROM 17 a of the memory card 17 is loaded to the RAM 24,and the event table 51 and the description data 52 having been loadedare read by the CPU core 21 as necessary when the terminal-side positiondetecting program 50 is in operation. The receiving time data 53 isgenerated and updated by the CPU core 21 when the terminal-side positiondetecting program 50 is in operation.

As shown in FIG. 24, the event table 51 shows whether or not each unitarea has a “describe” event and a “discover” event. As described abovewith reference to FIG. 20, the “describe” event automatically displays adescription text in the description display field 40. A description textcorresponding to each “describe” event is stored in the RAM 24 as thedescription data 52. As described above with reference to FIG. 21, the“discover” event displays an image on one of the floor displays 200 whenthe user touches the “discover” button 45. As shown in FIG. 25, thereceiving time data 53 stores a receiving time of each piece of thepositional information.

FIG. 26 shows a memory map of the RAM 301 included in the server 300.The RAM 301 stores a server-side position detecting program 55, currentmap image data 56, a “discover” event table 57, event picture data 58,“past” map image data 59, sightseeing course data 60, an “A course” flag61, and a “B course” flag 62. The server-side position detecting program55 stored in the hard disk 304 is loaded to the RAM 301, and theserver-side position detecting program 55 having been loaded is executedby the CPU 302. The current map image data 56, the “discover” eventtable 57, the event picture data 58, the “past” map image data 59, andthe sightseeing course data 60, which are all stored in the hard disk304, are loaded to the RAM 301 when the server-side position detectingprogram 55 is in operation, and read by the CPU 302 as necessary. The “Acourse” flag 61 and the “B course” flag 62 are generated and updated bythe CPU 302 when the server-side position detecting program 55 is inoperation.

The current map image data 56 represents map image data shown in FIG.18, for example. As shown in FIG. 27, the “discover” event table 57shows a unit area and picture data, included in the event picture data58, which corresponds thereto. The event picture data 58 represents dataof the event picture 47 shown in FIG. 21, for example. The “past” mapimage data 59 represents “past” image data displayed when the usertouches the “past” button 44. As shown in FIG. 28, the sightseeingcourse data 60 includes coordinates indicating a position of a travelingspot (i.e., a destination) in each of the “A course” and the “B course”,and an arrival flag showing whether the user arrives at the destination.The arrival flag shows whether or not the user visits the destination.

Next, with reference to a flowchart of FIG. 29, a flow of a processexecuted by the CPU core 21 based on the terminal-side positiondetecting program 50 will be described.

Firstly, in step S10, the CPU core 21 displays the initial image shownin FIG. 16 on the first LCD 11 and the second LCD 12 which are includedin the mobile terminal 10.

In step S11, a time count is started.

In step S12, a receiving time, of each piece of the positionalinformation, stored in the receiving time data 53 shown in FIG. 25 isreset to zero.

In step S13, it is determined whether either of the infrared receivingunits 34 has received an infrared ray from any of the positionalinformation transmitters 100. If either of the infrared receiving units34 has received an infrared ray, the process proceeds to step S14. Onthe other hand, if none of the infrared receiving units 34 has receivedan infrared ray, the process proceeds to step S16.

In step S14, the positional information is obtained from the receivedinfrared ray.

In step S15, the receiving time data 53 is updated by incrementing areceiving time of the obtained positional information.

In step S16, it is determined whether a predetermined time (e.g., 200ms) has passed since the time count is started in step S11. If thepredetermined time has passed, the process proceeds to step S17. On theother hand, if the predetermined time has not yet passed, the processreturns to step S13. Note that the predetermined time corresponds to atime period required for measuring a receiving frequency of each pieceof the positional information. If the predetermined time is set short, adetection interval of the current position of the mobile terminal 10becomes shorter, and a detection precision of the current position ofthe mobile terminal 10 becomes lower. On the other hand, if thepredetermined time is set long, the detection interval of the currentposition of the mobile terminal 10 becomes longer, and the detectionprecision of the current position of the mobile terminal 10 becomeshigher. Therefore, the predetermined time should be set at an optimumvalue depending on purpose.

In step S17, with reference to the receiving time data 53, the currentposition of the mobile terminal 10 is determined based on a receivingfrequency of each piece of the positional information. Although thepresent embodiment illustrates an example where it is determined thatthe mobile terminal 10 is positioned on a unit area corresponding to apiece of the positional information which has been most frequentlyreceived, the present invention is not limited thereto. As describedabove, the current position of the mobile terminal 10 may be determinedat a position which is more accurately indicated than that indicated bythe positional information.

In step S18, in accordance with the current position of the mobileterminal 10 determined in step S17, the image displayed on the first LCD11 or the second LCD 12 is changed. Specifically, with reference to theevent table 51, it is determined whether there is a “describe” event ora “discover” event, which corresponds to the current position of themobile terminal 10 determined in step S17. If there is a “describe”event, a description text is displayed in the description display field40 based on the description data 52 corresponding to the “describe”event. Also, if there is a “discover” event, a display mode of the“discover” button 45 is changed.

In step S19, an instruction inputted by the user via the touch panel 15or the operation switch unit 14 is obtained as operation information. Inthe present embodiment, any of an “A course” selecting instructioninputted by touching the “A course” selecting button 41, a “B course”selecting instruction inputted by touching the “B course” selectingbutton 42, an enlargement instruction inputted by touching the “enlarge”button 43, a “past” image display instruction inputted by touching the“past” button 44, and a “discover” event display instruction inputted bytouching the “discover” button 45 is obtained as the operationinformation. If no instruction is inputted by the user, the processproceeds to step S20 without obtaining the operation information.

In step S20, current positional information indicating the currentposition, of the mobile terminal 10, determined in step S17 and theoperation information obtained in step S19 are transmitted to the server300 via the wireless communication unit 33. If no operation informationis obtained in step S19, only the current positional information istransmitted to the server 300. Note that identification information ofthe mobile terminal 10 may be additionally transmitted, in step S20, tothe server 300 as necessary. If there are the plurality of mobileterminals 10, the identification information of the mobile terminals 10allows the server 300 to respectively recognize a current position ofeach of the mobile terminals 10. For example, users each carrying themobile terminal 10 can be respectively guided along the “A course” orthe “B course”. In order to realize the above example, groups of arrivalflags stored in the sightseeing course data 60, shown in FIG. 28, may begrouped for each of the mobile terminals 10 such that the server 300respectively determines traveling spots for each of the mobile terminals10.

In step S21, the terminal-side image is changed in accordance with theoperation information obtained in step S19 (e.g., the “B course”selecting button 42 is grayed out as shown in FIG. 17).

After step S21, the process returns to step S11.

Although the present embodiment described above illustrates an examplewhere the current position of the mobile terminal 10 is determined eachtime the predetermined time passes, and then the current positionalinformation indicating the current position of the mobile terminal 10 istransmitted to the server 300, the present embodiment is not limitedthereto. For example, the current position of the mobile terminal 10 maybe determined each time a total receiving time of the positionalinformation reaches a predetermined time, and then current positionalinformation indicating the current position of the mobile terminal 10may be transmitted to the server 300. Alternatively, the currentposition of the mobile terminal 10 may be determined, each time themobile terminal 10 receives any piece of the positional information,based on eight pieces of the positional information which have been mostrecently received, and then current positional information indicatingthe current position of the mobile terminal 10 may be transmitted to theserver 300.

Next, with reference to a flowchart of FIG. 30, a flow of a processexecuted by the CPU 302 based on the server-side position detectingprogram 55 will be described.

Firstly, in step S30, the CPU 302 displays the map image on each of thefloor displays 200 based on the current map image data 56.

In step S31, it is determined whether the current positional informationhas been received from the mobile terminal 10 via the wirelesscommunication unit 303. If the current positional information has beenreceived, the process proceeds step S32. On the other hand, if nocurrent positional information has been received, step S31 is repeateduntil any of the positional information is received.

In step S32, it is determined whether the operation information has beenreceived from the mobile terminal 10. If the operation information hasbeen received, the process proceeds to step S33. On the other hand, ifno operation information has been received, the process proceeds to stepS42.

In step S33, it is determined whether the operation informationrepresents the “A course” selecting instruction. If the operationinformation represents the “A course” selecting instruction, the processproceeds to step S34. On the other hand, if the operation informationdoes not represent the “A course” selecting instruction, the processproceeds to step S35.

In step S34, the “A course” flag 61 is turned on. Thereafter, theprocess proceeds to step S42.

In step S35, it is determined whether the operation informationrepresents the “B course” selecting instruction. If the operationinformation represents the “B course” selecting instruction, the processproceeds to step S36. On the other hand, if the operation informationdoes not represent the “B course” selecting instruction, the processproceeds to step S37.

In step S36, the “B course” flag 62 is turned on. Thereafter, theprocess proceeds to step S42.

In step S37, it is determined whether the operation informationrepresents the enlargement instruction. If the operation informationrepresents the enlargement instruction, the process proceeds to stepS38. On the other hand, if the operation information does not representthe enlargement instruction, the process proceeds to step S39.

In step S38, based on the current positional information received fromthe mobile terminal 10, an image, displayed on the floor display 200,which corresponds to the current positional information is enlarged, asshown in FIG. 22, centering on the current position of the mobileterminal 10. Thereafter, the process proceeds to step S42. Note that inthe example shown in FIG. 22, an image is enlarged centering on a unitarea on which the user (i.e., the mobile terminal 10) is positioned.However, in the case where the current positional information receivedfrom the mobile terminal 10 indicates a position which is moreaccurately indicated than that indicated by the unit area such as apoint within the unit area, the image may be enlarged centering on thepoint.

In step S39, it is determined whether the operation informationrepresents the “past” image display instruction. If the operationinformation represents the “past” image display instruction, the processproceeds to step S40. On the other hand, if the operation informationdoes not represent the “past” image display instruction (i.e., theoperation information represents the event picture display instruction),the process proceeds to step S41.

In step S40, based on the current positional information received fromthe mobile terminal 10 and the “past” map image data 59, a correspondingimage displayed on the floor display 200 is changed from the current mapimage to the “past” map image. Thereafter, the process proceeds to stepS42.

In step S41, based on the current positional information received fromthe mobile terminal 10, the “discover” event table 57 and the eventpicture data 58, the event picture 47 shown in FIG. 21, for example, isdisplayed on a corresponding floor display 200. Thereafter, the processproceeds to step S42.

In step S42, it is determined whether the operation mode of the server300 communicating with the mobile terminal 10 is the sightseeing mode.Specifically, when either of the “A course” flag 61 or the “B course”flag 62 is on, it is determined that the operation mode is thesightseeing mode. Whereas, when both of the “A course” flag 61 and the“B course” flag are off, it is determined that the operation mode is notthe sightseeing mode. If the operation mode of the server 300 is thesightseeing mode, the process proceeds to step S43. On the other hand,if the operation mode of the server 300 is not the sightseeing mode, theprocess returns to step S31.

In step S43, with reference to the current positional informationreceived from the mobile terminal 10 and the sightseeing course data 60,it is determined whether the mobile terminal 10 has arrived at adestination. For example, it is assumed that the mobile terminal 10 issequentially guided to a destination A, a destination B, and adestination C along the “A course”. When the mobile terminal 10 is to beguided to the destination C from the destination B, the currentpositional information of the mobile terminal 10 is compared, based onthe sightseeing course data 60, with coordinates (Xc, Yc) indicating aposition of the destination C, thereby determining whether the mobileterminal 10 has arrived at the destination C. If the mobile terminal 10has arrived at the destination, the process proceeds to step S44. On theother hand, if the mobile terminal 10 has not yet arrived at thedestination, the process proceeds to step S45.

In step S44, an arrival flag corresponding to the destination at whichthe mobile terminal 10 has arrived is turned on.

In step S45, based on coordinates indicating positions of destinationsshown in the sightseeing course data 60, the arrow 46 indicating, asshown in FIG. 18, a direction of one of the destinations is combinedwith the map image displayed on the floor display 200 corresponding tothe current positional information received from the mobile terminal 10.

After step S45, the process returns to step S31. Note that the imageenlarged in step S38 and the “past” image changed in step S40 may bedisplayed only for a constant period of time so as to return to originalimages after a predetermined time passes.

As described above, according to the present embodiment, the imagedisplayed on the first LCD 11 or the second LCD 12 of the mobileterminal 10 is automatically changed in accordance with a currentposition of the mobile terminal 10. Furthermore, when the user inputs aninstruction via the touch panel 15, the map image displayed on one ofthe floor displays 200 on which the user stands is changed in accordancewith the inputted instruction. Thus, according to the presentembodiment, it becomes possible to provide a highly interesting andnovel position detecting system.

Although the present embodiment illustrates an example where thepositional information is transmitted from the positional informationtransmitters 100 by means of infrared rays, the present embodiment isnot limited thereto. The positional information may be transmitted bysignals other than the infrared rays. Furthermore, in the presentembodiment, wireless communication is used between the mobile terminal10 and the server 300. However, instead of the wireless communication, acommunication cable may be used for communicating between the mobileterminal 10 and the server 300.

Although the present embodiment illustrates an example where a pluralityof infrared rays are transmitted from each of the positional informationtransmitters 100 at an interval consisting of four phases shown in FIGS.11 to 14, in order to prevent interference between the infrared raystransmitted from the positional information transmitters 100, thepresent embodiment is not limited thereto. For example, in the casewhere a diameter of a receiving area of each piece of the positionalinformation is in a range from two to three times as long as a length ofa side of a unit area, the infrared rays may be transmitted from each ofthe positional information transmitters 100 at an interval consisting ofnine phases; i.e., the nine phases including, when n and m are integers,a first phase for transmitting positional information (0+3m, 0+3n), asecond phase for transmitting positional information (0+3m, 1+3n), athird phase for transmitting positional information (0+3m, 2+3n), afourth phase for transmitting positional information (1+3m, 0+3n), afifth phase for transmitting positional information (1+3m, 1+3n), asixth phase for transmitting (1+3m, 2+3n), a seventh phase fortransmitting (2+3m, 0+3n), an eighth phase for transmitting (2+3m,1+3n), and a ninth phase for transmitting (2+3m, 2+3n).

In the present embodiment described above, a transmission timing of apiece of the positional information transmitted to a unit area and atransmission timing of another piece of the positional informationtransmitted to an adjacent unit area are shifted from each other.Alternatively, in order to prevent interference between infrared raystransmitted from the positional information transmitters 100, afrequency band of an infrared ray transmitted to a unit area may be setso as to be different from that of another infrared ray transmitted toits adjacent unit area. In the above case, the mobile terminal 10 has afunction of simultaneously receiving a plurality of infrared rays havingdifferent communication bands from each other, thereby making itpossible to prevent a receiving error of an infrared ray from occurringdue to the interference of the infrared rays, without shifting atransmission timing at which a piece of the positional information istransmitted to a unit area from that at which another piece of thepositional information is transmitted to an adjacent unit area.

Furthermore, although the present embodiment illustrates an examplewhere the positional information is transmitted from the positionalinformation transmitters 100, the present embodiment is not limitedthereto. When necessary, information other than the positionalinformation may be additionally transmitted as additional information.For example, any information outputted from the server 300 may betransmitted to each of the positional information transmitters 100 viathe transmitter control device 400, and then each of the positionalinformation transmitters 100 may transmit the information, as additionalinformation, together with the positional information.

Although the present embodiment illustrates an example where the mapimage is displayed on the entirety of the floor displays 200, thepresent embodiment is not limited thereto. Hereinafter, several othervariants of the present embodiment will be described.

(First Variant)

In a first variant of the present embodiment, a virtual pond isdisplayed on the entirety of the plurality of floor displays 200. Animage of the pond displayed on the floor displays 200 is generated bycomputer graphics. There are a school of fish in the pond, and the CPU302 of the server 300 controls a movement of each of the fish.Specifically, the movements of the fish are controlled so as to swimaway when a user carrying the mobile terminal 10 comes close to thefish. The CPU 302 can determine whether the user comes close to a fishby comparing the current positional information transmitted from themobile terminal 10 with a current position of the fish. Note that a fishswims away so as to move away from the user. For example, when the usermoves from a unit area (1, 0) to a unit area (1, 1) while a fish isdisplayed in the unit area (1, 1), the CPU 302 which detects the usermoving from the unit area (1, 0) to the unit area (1, 1) causes the fishto move from the unit area (1, 1) to a unit area (1, 2).

Furthermore, a “bait” button is displayed on the second LCD 12 of themobile terminal 10. When the user touches the “bait” button, a fishcomes close to the user's feet. Specifically, when the CPU 302 detectsthe “bait” button touched by the user based on the operation informationtransmitted from the mobile terminal 10, the CPU 302 causes a fish tomove to a position corresponding to the current positional informationtransmitted from the mobile terminal 10.

Still furthermore, a specific area (e.g., a unit area (2, 2)) on thepond has a lotus leaf floated thereon, and there are a group of frogs onthe lotus leaf. When the user carrying the mobile terminal 10 moves tothe unit area (2, 2), the CPU core 21 of the mobile terminal 10 outputsa song (e.g., “frog song”) from the right and left speakers 30 a and 30b included in the mobile terminal 10. Whether the user carrying themobile terminal 10 moves to the unit area (2, 2) can be determined basedon the positional information transmitted from the positionalinformation transmitters 100. Note that each of the positionalinformation transmitters 100 transmits, in addition to the positionalinformation, a song output starting signal at an interval of a constantperiod of time. The song output starting signal is transmitted at theinterval of the period of time corresponding to two bars of the songoutputted by the CPU core 21. When the user carrying the mobile terminal10 moves to the unit area (2, 2), and then the mobile terminal 10receives the song output starting signal from one of the positionalinformation transmitters 100, the CPU core 21 starts to output theaforementioned song. As a result, for example, when two or more users,each of which carries the mobile terminal 10, are gathered on the unitarea (2, 2) at different timings, the songs are outputted from themobile terminals 10 so as to be shifted from each other by an integralmultiple of the period of time corresponding to the two bars of thesong. Thus, it becomes possible to obtain an interesting effect that theplurality of mobile terminals 10 on the unit area (2, 2) “troll” thesong.

Still furthermore, a “ripple” button is displayed on the second LCD 12of the mobile terminal 10. When the user touches the “ripple” button, adisplay control is performed such that a ripple spreads, from the user'sfeet, across a water surface displayed on the entirety of the floordisplays 200.

(Second Variant)

In a second variant, a virtual garden is displayed on the entirety ofthe plurality of floor displays 200. An image of the garden displayed onthe floor displays 200 is generated by computer graphics. A plurality oftreasures are dispersedly buried under the ground of the garden. When auser carrying the mobile terminal 10 comes close to a location at whicha treasure is buried, a “dig” button is displayed on the second LCD 12of the mobile terminal 10. Then, when the user touches the “dig” button,one of the floor displays 200 on which the user stands displays ananimation in which the ground displayed thereon is dug and then thetreasure appears. As described above, the user can play a treasure hunt.Note that a mechanism which displays the “dig” button when the usercomes close to a location at which a treasure is buried can be realizedin a similar manner to that of the “discover” button described above.Also, a mechanism which displays the animation in which the treasureappears can be realized in a similar manner to that of the event picturedescribed above.

While the example embodiment presented herein has been described indetail, the foregoing description is in all aspects illustrative and notrestrictive. It is understood that numerous other modifications andvariations can be devised without departing from the scope of theembodiment.

1. A position detecting system comprising: an information transmissiondevice for transmitting predetermined information; a mobile terminal forreceiving the predetermined information; and a control device capable ofcommunicating with the mobile terminal, the mobile terminal including:first display unit for displaying a first image; first receivingprogrammed logic circuitry for receiving the predetermined informationtransmitted from the information transmission device; first imageprocessing programmed logic circuitry for changing the first image inaccordance with the predetermined information received by the firstreceiving programmed logic circuitry; operation elements for acceptingan instruction inputted by a user; and transmission programmed logiccircuitry for transmitting, to the control device, current positionalinformation corresponding to the predetermined information received bythe first receiving programmed logic circuitry, said current positionalinformation generated by current positional information generatingprogrammed logic circuitry, and operation information indicating theinstruction inputted by the user through the operation elements, thecontrol device arranged separately from the mobile terminal and theinformation transmission device and including: second display unit fordisplaying a second image; second receiving programmed logic circuitryfor receiving the current positional information and the operationinformation transmitted from the mobile terminal; and second imageprocessing programmed logic circuitry for changing the second image inaccordance with the current positional information and the operationinformation received by the second receiving programmed logic circuitry,wherein the information transmission device transmits the predeterminedinformation for a predetermined number of times at an interval of apredetermined period of time, and the current positional informationgenerating programmed logic circuitry measures the number of times eachpiece of the predetermined information was received by the firstreceiving programmed logic circuitry, and generates the currentpositional information based on said measured number of times each pieceof the predetermined information was received.
 2. The position detectingsystem according to claim 1, wherein the current positional informationgenerating programmed logic circuitry generates the current positionalinformation, based on a ratio of the number of times each piece of thepredetermined information is successfully received, for thepredetermined period of time, by the first receiving programmed logiccircuitry, to the total number of times each piece of the predeterminedinformation is transmitted for the predetermined period of time.
 3. Theposition detecting system according to claim 2, wherein the currentpositional information generating programmed logic circuitry calculatesa weighted average of the predetermined information by averaging thepredetermined information received for the predetermined period of timeby the first receiving programmed logic circuitry, in accordance withthe receiving frequency of the predetermined information, such that thecurrent positional information generating programmed logic circuitrygenerates the current positional information.
 4. A position detectingsystem comprising: an information transmission device for transmittingpredetermined information; a mobile terminal for receiving thepredetermined information; and a control device capable of communicatingwith the mobile terminal, the mobile terminal including: first displayunit for displaying a first image; first receiving programmed logiccircuitry for receiving the predetermined information transmitted fromthe information transmission device; first image processing programmedlogic circuitry for changing the first image in accordance with thepredetermined information received by the first receiving programmedlogic circuitry; operation elements for accepting an instructioninputted by a user; and transmission programmed logic circuitry fortransmitting, to the control device, current positional informationcorresponding to the predetermined information received by the firstreceiving programmed logic circuitry, said current positionalinformation generated by current positional information generatingprogrammed logic circuitry, and operation information indicating theinstruction inputted by the user through the operation elements, and thecontrol device arranged separately from the mobile terminal and theinformation transmission device and including: second display unit fordisplaying a second image; second receiving programmed logic circuitryfor receiving the current positional information and the operationinformation transmitted from the mobile terminal; and second imageprocessing programmed logic circuitry for changing the second image inaccordance with the current positional information and the operationinformation received by the second receiving programmed logic circuitry,wherein the first image includes an image, and the first imageprocessing programmed logic circuitry changes a display mode of theimage between a first display mode indicating the image is selectable bythe user and a second display mode indicating the image is notselectable by the user in accordance with the predetermined informationreceived by the first receiving programmed logic circuitry.
 5. Anon-transitory computer-readable physical storage medium having tangiblyrecorded thereon a position detecting program executed by a computer ofa mobile terminal and a computer of a control device in a positiondetecting system, the position detecting system comprising: aninformation transmission device for transmitting predeterminedinformation; a mobile terminal for receiving the predeterminedinformation; and a control device capable of communicating with themobile terminal, the position detecting program instructing the computerof the mobile terminal to perform: first display control for causing afirst display unit of the mobile terminal to display a first image;first receiving control for causing first receiving programmed logiccircuitry of the mobile terminal to receive the predeterminedinformation transmitted from the information transmission device; firstimage processing for changing the first image in accordance with thepredetermined information received by the first receiving programmedlogic circuitry; and transmission control for causing programmed logiccircuitry of the mobile terminal to transmit, to the control device,current positional information corresponding to the predeterminedinformation received by the first receiving programmed logic circuitry,said current positional information generated by current positionalinformation generating programmed logic circuitry, and operationinformation indicating an instruction inputted by the user throughoperation elements of the mobile terminal, the control device arrangedseparately from the mobile terminal and the information transmissiondevice, and the position detecting program instructing the computer ofthe control device to perform: second display control for causing asecond display unit of the control device to display a second image;second receiving control for causing second receiving programmed logiccircuitry of the control device to receive the current positionalinformation and the operation information transmitted from the mobileterminal; and second image processing for changing the second image inaccordance with the current positional information and the operationinformation received by the second receiving programmed logic circuitry,wherein the information transmission device transmits the predeterminedinformation for a predetermined number of times at an interval of apredetermined period of time, and the current positional informationgenerating programmed logic circuitry measures the number of times eachpiece of the predetermined information was received by the firstreceiving programmed logic circuitry, and generates the currentpositional information based on said measured number of times each pieceof the predetermined information was received.
 6. A non-transitorycomputer-readable physical storage medium having tangibly recordedthereon a position detecting program executed by a computer of a mobileterminal and a computer of a control device in a position detectingsystem, the position detecting system comprising: an informationtransmission device for transmitting predetermined information; a mobileterminal for receiving the predetermined information; and a controldevice capable of communicating with the mobile terminal, the positiondetecting program instructing the computer of the mobile terminal toperform: first display control for causing a first display unit of themobile terminal to display a first image; first receiving control forcausing first receiving programmed logic circuitry of the mobileterminal to receive the predetermined information transmitted from theinformation transmission device; first image processing for changing thefirst image in accordance with the predetermined information received bythe first receiving programmed logic circuitry; and transmission controlfor causing transmission programmed logic circuitry of the mobileterminal to transmit, to the control device, current positionalinformation corresponding to the predetermined information received bythe first receiving programmed logic circuitry, said current positionalinformation generated by current positional information generatingprogrammed logic circuitry, and operation information indicating aninstruction inputted by the user through operation elements of themobile terminal, and the control device arranged separately from themobile terminal and the information transmission device, and theposition detecting program instructing the computer of the controldevice to perform: second display control for causing a second displayunit of the control device to display a second image; second receivingcontrol for causing second receiving programmed logic circuitry of thecontrol device to receive the current positional information and theoperation information transmitted from the mobile terminal; and secondimage processing for changing the second image in accordance with thecurrent positional information and the operation information received bythe second receiving programmed logic circuitry, wherein the first imageincludes an image, and the first image processing changes a display modeof the image between a first display mode indicating the image isselectable by the user and a second display mode indicating the image isnot selectable by the user in accordance with the predeterminedinformation received by the first receiving programmed logic circuitry.